1. Field of the Invention
The present invention relates to the safe operation of conveyor systems, and more particularly relates to safety devices for conveyors used at a retail check-out counter.
2. Background of the Related Art
Conveyors having moving belts are commonly used in grocery stores, retail merchandise stores and in shipping and distribution centers to reliably move articles selected and deposited thereon to a destination, such as a clerk, a scanner or an accumulation area. Usually, a conveyor belt is a generally continuous loop of fabric or other pliable material extending from a first roller to a second roller so that when one or more of the rollers are rotated, such as by a motor, the vertically upwardly disposed top side of the belt provides a moving deck on which a handler or consumer may place articles to be shipped, distributed or purchased. The opposite, or bottom, side of the conveyor belt is usually parallel to the top side, but generally not visible to persons using the conveyor. A horizontal support surface, such as a table, is generally disposed intermediate the top side and the bottom side of the conveyor belt, intermediate the first roller and the second roller, to support the movable top side of the conveyor belt and the articles transported thereon.
The conveyor belt may be continually driven about its path around the first roller at an intake end and the second roller at a discharge end to provide a moving deck to support and transport articles placed thereon. The first roller is generally positioned at the intake end of the conveyor where the handler or consumer deposits the articles onto the conveyor, and the second roller is generally positioned at a discharge end of the conveyor adjacent, for example, to the top of a descending run-out ramp. At the discharge end of the conveyor, the incoming (indicating direction of movement relative to a person standing at the discharge end) conveyor belt bends around, and conforms to the circular exterior of the second roller. The conveyor belt wraps about 180 degrees on the first roller and also on the second roller, each time to reverse its direction of travel from the bottom side to the top side (at the first roller), or from the top side to the bottom side (at the second roller).
The run-out ramp may be a downwardly sloped surface comprising, for example, a sheet of stainless steel, a series of parallel tubular rollers or a plurality of parallel sets of wheels, each set of wheels having a common axle. Articles discharged from the discharge end of the conveyor onto a first end of the run-out ramp may slide or roll down the run-out ramp away from the first end, and accumulate at an accumulation area at or near the second end to await bagging, packaging, further processing and/or retrieval after a completed transaction.
There is generally a gap between the discharge end of the conveyor and the first end of the run-out ramp, and this gap can pose a hazard to articles or personnel. Articles packaged in loose fitting plastic or fabric bags, or in enclosures with loose or protruding portions, may become drawn into the gap between the discharge end of the conveyor and the first end of the run-out ramp, and these articles may become damaged or torn. Under unattended conditions, clothing, jewelry, fingers, hands or even long hair may become inadvertently drawn into the gap by the conveyor, thereby resulting in damage to articles or personal injury. To prevent damage to articles or injury to persons, the gap between the discharge end of the conveyor and the first end of the run-out ramp is generally bridged by a transition plate seated within the gap to prevent articles from being drawn into the gap between the second roller of the conveyor and the adjacent first end of the run-out ramp. The transition plate is generally removable from its seated position within the gap to enable the removal of articles or debris that may be drawn into the gap or trapped under the transition plate.
Many check-out counters are unattended, and others are loosely attended by untrained personnel that may not appreciate the danger of damage to articles or injury to persons that can occur if articles are drawn into the gap. In some cases, the transition plate may not be promptly and safely restored to its seated position, thereby increasing the chances of articles being drawn into the gap adjacent to the second roller of the conveyor.
Conventional transition plates may be secured within the gap using fasteners or other devices to prevent unseating and/or removal. A transition plate may be secured in the seated position using fasteners, such as screws, but these may be time-consuming to remove to free articles that may be trapped between the transition plate and the conveyor belt. These types of transition plates may become lost or misplaced after removal. Alternatively, a transition plate may be hingedly attached to the check-out counter to prevent removal of the transition plate from check-out counter. A hinged transition plate may be pivoted from its seated position to a removed position to allow an attendant to remove articles or to clear debris, and then pivoted back to the seated position for resumption of operations. This prevents the transition plate from becoming lost or misplaced. However, if a hinge is positioned to pivot the transition plate upwardly from the gap and toward the conveyor, rather than upwardly from the gap and toward the run-out ramp, the hinge can actually exacerbate the hazard by creating a narrow pinch point between the transition plate and the discharge end of the conveyor upon pivoting of the transition plate from its seated position.
Other conventional transition plates may be retained within the gap using spring-loaded retainers that will, upon being subjected to a sufficient dislodging force, surrender the transition plate from its seated position when the dislodging force exceeds the retention force of the spring(s). For example, spring-loaded retainers for holding the transition plate in its seated position between the conveyor discharge and the run-out ramp may become damaged, broken or detached, and the transition plate may become insufficiently seated within the gap. This can cause a larger opening between the discharge end of the conveyor such that the transition plate will catch on or trap more articles and present a greater danger personal injury.
In some designs, such as the spring-loaded retainer embodiment discussed above, the transition plate may be retained in its seated position within the gap in a manner that allows it to break-away and dislodge by an unseating force applied as if by an article caught between the conveyor belt and the transition plate. The problem with these transition plates and related retainers is that the conveyor may continue to operate so that, if an article is already trapped or drawn into the gap, the conveyor might continue in motion, pulling the article further into the gap and causing possible damage, and making it much more difficult to rectify.
An attempted solution to the above-referenced problem provides a mechanically operated switch to interrupt the power source to a drive motor that drives the conveyor belt about the first roller and the second roller. A mechanical switch may comprise a portion that is displaced to engage a switch and, for example, close an electrical circuit to the motor, when the transition plate is in its seated position within the gap. However, these mechanical switches may be easily overridden or compromised by inserting an object to hold the switch in the closed position.